Mean CO2 Concentration Research Articles

The importance of freshwater systems to the net atmospheric exchange of carbon dioxide and methane with a rapidly changing high Arctic watershed

Abstract. A warming climate is rapidly changing the distribution and exchanges of carbon within high Arctic ecosystems. Few data exist, however, which quantify exchange of both carbon dioxide (CO2) and methane (CH4) between the atmosphere and freshwater systems, or estimate freshwater contributions to total catchment exchange of these gases, in the high Arctic. During the summers of 2005 and 2007–2012, we quantified CO2 and CH4 concentrations in, and atmospheric exchange with, common freshwater systems in the high Arctic watershed of Lake Hazen, Nunavut, Canada. We identified four types of biogeochemically distinct freshwater systems in the watershed; however mean CO2 concentrations (21–28 µmol L−1) and atmospheric exchange (−0.013 to +0.046 g C–CO2 m−2 day−1) were similar between these systems. Seasonal flooding of ponds bordering Lake Hazen generated considerable CH4 emissions to the atmosphere (+0.008 g C–CH4 m−2 day−1), while all other freshwater systems were minimal emitters of this gas (< +0.001 g C–CH4 m−2 day−1). When using ecosystem-cover classification mapping and data from previous studies, we found that freshwaters were unimportant contributors to total watershed carbon exchange, in part because they covered less than 10 % of total area in the watershed. High Arctic watersheds are experiencing warmer and wetter climates than in the past, which may have implications for moisture availability, landscape cover, and the exchange of CO2 and CH4 of underproductive but expansive polar semidesert ecosystems.

Field study on the objective evaluation of sleep quality and sleeping thermal environment in summer

To validate the feasibility of Actiwatch 2 (AW2) to measure sleep quality in thermal comfort researches, five parameters drawn from AW2 and the subjective evaluation of sleep quality, sleep quality vote (SQV) were collected. Furthermore, to explore the effect of thermal environment and IAQ on sleep quality with AW2, the standard effective temperature (SET) was induced to evaluate the integrated effect of the sleeping thermal environment and CO2 was to indicate the freshness of air quality. Ambient temperature, relative humidity, mean radiant temperature, air velocity and CO2 concentration were monitored in 6 bedroom of different type, including natural-ventilated rooms and air-conditioned rooms, during the hot season in Beijing for nearly one month. The occupant bedding system, posture habit and thermal sensation vote before sleep (BTSV) and after sleep (ATSV) of 3 female and 3 male subjects were recorded with questionnaire. The results showed that some of the sleep quality parameters measured by AW2 accorded with the subjective evaluation; Thermal environment had an effect on sleep quality according to the significant correlations between SET and the sleep quality parameters measured by AW2; The thermoneutral range of SET in sleeping condition was between 29.1–29.7°C, based on which the thermal insulation of bedding system (Icl) was recommended to be 0.96–1.08clo.

Indoor Air Quality in Kitchens in Rural China

Abstract Field measurements were conducted to assess the indoor air quality in kitchens using traditional stove without chimney, improved stove with chimney, and LPG stove in rural Hubei Province, China. Results showed that without cooking activity, concentrations of NO2, SO2, and CO in all kitchens met the national standard of China. On the other hand, PM2.5 in kitchens using LPG stove and traditional stove was slightly higher than the standard during the period without cooking activity. Cooking activity increased PM2.5 mass concentration and particle number concentration in all kitchens, especially in kitchen using traditional stove. With cooking activity, PM2.5 mass concentrations were well above the standard. Increase in CO, NO2, and SO2 concentrations during cooking was not as significant as PM2.5. Except for CO in traditional stove, mean concentrations of CO, NO2, and SO2 were below the standard even during cooking.

Landscape control on the hydrogeochemistry of As, Co and Pb in a boreal stream network

In a boreal stream network, stream water concentrations of As, Co and Pb (filtered, <0.4μm) of 10 nested streams were studied during two consecutive years in order to evaluate the influence of land cover on the temporal and spatial variability of metal concentrations and speciation. Mean concentrations of Co and Pb showed significant but contrasting relationship to landscape type, while As concentrations were not related to landscape type. Highest concentrations of Pb were found in the wetland dominated streams (>30% wetland), which was suggested to be controlled by atmospheric deposition in combination with high DOC release from the wetlands. For Co, the highest concentrations were found in the forest dominated sites (>98% forest), which were attributed to the weathering of minerogenic sources. Contrasting response to runoff events could also be related to landscape type; during the spring flood, decreasing concentrations of As, Co and Pb were observed in the wetland dominated catchments due to dilution, while increasing concentrations during spring flood were observed in the mixed catchments (2–30% wetland) and to some degree in the forested catchments, probably due to flushing of the organic-rich riparian sources. Further, metal speciation was calculated using the geochemical equilibrium model Visual MINTEQ. This suggests that dissolved inorganic species of As and Co dominated in headwater streams with low pH while DOC had a major influencing role for Pb. In the larger mixed streams where pH was higher and precipitation of e.g. colloidal Fe and Mn (hydr)oxides was favoured, the major influencing factor was instead adsorption to colloidal Fe for As and Pb, while association to organic matter and colloids of e.g. Mn influenced the concentrations of Co. We thus conclude that landscape type and the magnitude of the runoff events are of great importance for the spatial and temporal variations of As, Co and Pb in this boreal stream network. Projected climate change, with increasing runoff, may therefore influence riverine concentrations and fluxes differently, depending on the prevailing landscape type.

Spiders in mofette fields—Survival of the toughest in natural carbon dioxide springs?

In mofette fields, natural carbon dioxide springs, organisms have to stand extreme CO2 concentrations up to 100%. These hostile conditions are spatially small-scaled and further influenced by earth tides, wind and temperature. The present project investigated the influence of increased atmospheric CO2 concentration on spiders as representatives of above-ground organisms by means of pitfall traps in three mofette fields, differing in habitat conditions in the Plesná valley, eastern Cheb Basin, Czech Republic.Among the 71 recorded spider species four were rarely found in the Czech Republic. A canonical correspondence analysis revealed significant influences of environmental parameters on the spider assemblages. Two groups of spiders are clearly distinguishable, one being positively influenced by humidity and the second by temperature. A cluster analysis showed distinct and congruent results: spider assemblages of pitfall traps at spots with a mean CO2 concentration above 7.6% grouped close together and this grouping was independent of site. At >7.6% CO2 significantly fewer individuals and species were found in comparison to areas with lower CO2 concentration. Between 2.5 and 10% CO2, spiders indicated increased CO2 concentrations much more sensitively than endogeic organisms (Nematoda, Collembola) in a nearby mofette field. Unlike in nematodes, collembolans and plants, no mofettovageous or mofettophilous spiders were detected. In contrast to humidity, CO2 concentration and temperature, the vegetation cover was not among the factors, which significantly influenced spiders. This is explained by the fact that mofettophilous plants occurred at spots where almost no spiders could live. In a field experiment, most Pardosa pullata males tested passed a 30cm long corridor with increased carbon dioxide concentration. These results and that of pitfall traps showed that relatively large and wandering specimens respectively were able to transit moderately hostile spots. Further experiments are necessary to find out if there is any active avoidance of high-CO2 areas by spiders.

Experimental study of torrefied pine as a gasification fuel using a bubbling fluidized bed gasifier

Torrefied biomass has higher C/O ratio, resulting in improved heating value and reduced hygroscopic nature of the biomass, thus enabling longer storage times. In the southeastern United States, pine is has been identified as a potential feedstock for energy production. The objective of this study was to understand the performance of torrefied pine as a gasification fuel in a bench-scale bubbling fluidized bed gasifier. The gasification of torrefied pine was carried out at 790, 935 and 1000 °C and three equivalence ratios (ERs: 0.20, 0.25 and 0.30). The effect of process variables were studied based on i) products yield, ii) syngas composition iii) syngas energy content, and iv) contaminants. The mean concentration of CO increased with an increase in temperature, but was not statistically significant. On the other hand, H2 concentration increased whereas CH4 concentration decreased significantly with an increase in temperature from 790 to 935 °C. Further, with an increase in ER from 0.20 to 0.30, only CO2 concentrations increased in the syngas. Results from torrefied pine were compared with raw pine gasification, and it was observed that torrefied pine gasification led to much higher char yield (more than twice) than pine; however, it produced less than half as much tar.

Air Quality Monitoring in Uyo Metropolis, Akwa Ibom State, Niger Delta Region of Nigeria

Assessment of air quality in Uyo metropolis was carried out by monitoring levels of nitrogen (IV) oxide, sulphur (IV) oxide, hydrogen sulphide, carbon (II) oxide, ammonia, chlorine gas and suspended particulate matter at four major locations within the study area for one week. Results obtained indicated higher mean concentrations of CO, NH3 and Cl2 in the morning hours, NO2, H2S and SPM in the afternoon while, SO2 did not vary considerably between these periods. Levels of these air particulates were above their recommended standards by FEPA indicating their nuisance status. However, Air quality index classified NO2 and SO2 in the very poor class, CO in moderate class while NH3 and SPM were in the very good category. Correlation analyses showed that, NO2 and SO2 exhibited strong positive relationships with H2S, CO and Cl2. Hydrogen sulphide showed common source and strong correlation with CO, NH3 and Cl2. Carbon (II) oxide correlated positively and significantly with Cl2 and SPM while, chlorine indicated significant positive association with SPM. Principal component analysis indicated two (2) major factors with 91.39% of total variance. Factor 1 represented impacts of fuel combustion and vehicular emissions whereas; factor 2 represented influences of organic matter decomposition and petroleum processing.

Effects of plastic film mulching on soil greenhouse gases (CO2, CH4 and N2O) concentration within soil profiles in maize fields on the Loess Plateau, China

AbstractTo better understand the effects of plastic film mulching on soil greenhouse gases (GHGs) emissions, we compared seasonal and vertical variations of GHG concentrations at seven soil depths in maize (Zea mays L.) fields at Changwu station in Shaanxi, a semi-humid region, between 2012 and 2013. Gas samples were taken simultaneously every one week from non-mulched (BP) and plastic film-mulched (FM) field plots. The results showed that the concentration of GHGs varied distinctly at the soil-atmosphere interface and in the soil profile during the maize growing season (MS). Both carbon dioxide (CO2) and nitrous oxide (N2O) concentrations increased with increasement of soil depth, while the methane (CH4) concentrations decreased with increasement of soil depth. A strong seasonal variation pattern was found for CO2 and N2O concentrations, as compared to an inconspicuous seasonal variation of CH4 concentrations. The mean CO2 and N2O concentrations were higher, but the mean CH4 concentration in the soil profiles was lower in the FM plots than in the BP plots. The results of this study suggested that plastic film mulching significantly increased the potential emissions of CO2 and N2O from the soil, and promoted CH4 absorption by the soil, particularly during the MS.

Assessment of Heavy Metals Contamination in Roadside Soil Dust in Doon Valley, Uttarakhand

The accumulation of heavy metals in soil at roadside has been studied by the analysis of top soil/dust samples. Concentration of the elements Co, Cr, Pb and Cd were measured on 39 top soil/dust samples collected from near the highways, industrial area and control site. The samples were analysed for Zn, Cu, Fe, Mn, Pb, Cd, Ni, and Cr by using atomic absorption spectrophotometer (AAS). The mean concentrations of Co, Cr, Pb and Cd were 0.390, 0.090, 2.195 and 0.094 mg kg-1, respectively. Data obtained from analysis, were statistically examined to know the distribution of metals in different highways and industrial area. The results showed that the topsoil/dust near the highway and industrial sites had significantly enrichment particularly Pb than control sites.

Comparing Motivational Interviewing-Based Treatment and its combination with Nicotine Replacement Therapy on smoking cessation in prisoners: a randomized controlled clinical trial.

BackgroundThe prevalence of smoking is much higher in prisoners than it is in the general population. Prisoners who smoke cause many health problems for themselves and other prisoners. Therefore, we should help them stop smoking.ObjectiveTo compare the effects of motivational interviewing-based (MI-based) treatment and its combination with nicotine replacement therapy (NRT) on smoking cessation in prisoners at Mashhad Central Prison.MethodsThe study was designed as a double-blind, randomized, controlled clinical trial, and it began in February 2013 and ended in February 2014. Two hundred and thirteen prisoners met the inclusion criteria and were enrolled in the study. They were divided randomly into three groups, i.e., MI-based treatment, MI with NRT, and the control group, which didn’t receive any therapy. The outcome measures were reported after intervention and at a 90-day follow-up, and changes in the CO levels in expired air and nicotine dependency were measured.ResultsThe average age of the subjects was 37.59 ± 8.76, and their mean duration of imprisonment was 3.3 ± 1.90 years. They smoked an average of 21.84 ± 8.72 cigarettes per day. Analysis of the concentration of CO in expired air in the pre-test, post-test, and at the follow-up for the three groups showed that the variations in the mean CO concentrations in the MI group and the MI with NRT group at the pre-test and at the post-test were statistically significant (p < 0.001), but no significant changes occurred between the post-test and the follow-up (p > 0.050). In addition, the results indicated that CO concentration in expired air in the MI with NRT group was statistically significant, with better efficacy of smoking cessation, compared with control group and the MI group after the follow-up (p = 0.02).ConclusionsMotivational interviewing combined with NRT for smoking cessation is more effective than MI alone, and it resulted in a significant decrease in the CO concentration in expired air at the 90-day follow-up.

Risk Factors for Asthma Hospitalization among Adults and Elderly

Joint effect of biological (pollen) and chemical air pollutants on asthma emergency room (ER) visits was analyzed for Szeged region of Southern Hungary. Our database of a nine-year period (1999-2007) includes daily number of asthma emergency room (ER) visits, and daily mean concentrations of CO, PM 10 , NO, NO 2 , O 3 and SO 2 , furthermore two pollen variables (Ambrosia and total pollen excluding Ambrosia), as well. The analysis was performed for ER visits of asthma bronchiale using two age groups (adults and the elderly) of males and females for three seasons. Factor analysis was performed in order to clarify the relative importance of the pollutant variables affecting asthma ER visits. Asthma ER visits denote notably stronger associations with the pollutants in adult male than in adult female patients both for the pollen season of Ambrosia and the pollen-free season. Furthermore, adults are substantially more sensitive to severe asthma attack than the elderly for the season of total pollen excluding Ambrosia pollen. The joint effect of the chemical and pollen variables is the highest for the asthma ER cases in the pollen season of Ambrosia, basically due to the extra impact of the total pollen excluding Ambrosia pollen and partly due to Ambrosia pollen. A nonparametric regression technique was applied to discriminate between events of ER visit – no ER visit using pollen and chemical pollutants as explaining variables. Based on multiple correlations, the strongest relationships between ER visits and pollutants are observed during the pollen-free season. The elderly group with asthma bronchiale is characterized by weaker relationships between ER visits and pollutants compared to adults. Ratio of the number of correct decisions on the events of ER visit – no ER visit is lowest for the season of total pollen excluding Ambrosia pollen. Otherwise, similar conclusions hold as those received by multiple correlations.

Seasonal variations of outdoor air pollution and factors driving them in the school environment in rural Bhutan

A quantitative understanding of outdoor air quality in school environments is crucial given that air pollution levels inside classrooms are significantly influenced by outdoor pollution sources. To date, only a handful of studies have been conducted on this important topic in developing countries. The aim of this study was to quantify pollutant levels in the outdoor environment of a school in Bhutan and assess the factors driving them. Measurements were conducted for 16 weeks, spanning the wet and dry seasons, in a rural school in Bhutan. PM10, PM2.5, particle number (PN) and CO were measured daily using real-time instruments, while weekly samples for volatile organic compounds (VOCs), carbonyls and NO2 were collected using a passive sampling method. Overall mean PM10 and PM2.5 concentrations (μg/m3) were 27 and 13 for the wet, and 36 and 29 for the dry season, respectively. Only wet season data were available for PN concentrations, with a mean of 2.56 × 103 particles/cm3. Mean CO concentrations were below the detection limit of the instrumentation for the entire measurement period. Only low levels of eight VOCs were detected in both the wet and dry seasons, which presented different seasonal patterns in terms of the concentration of different compounds. The notable carbonyls were formaldehyde and hexaldehyde, with mean concentrations (μg/m3) of 2.37 and 2.41 for the wet, and 6.22 and 0.34 for the dry season, respectively. Mean NO2 concentration for the dry season was 1.7 μg/m3, while it was below the detection limit of the instrumentation for the wet season. The pollutant concentrations were associated with a number of factors, such as cleaning and combustion activities in and around the school. A comparison with other school studies showed comparable results with a few of the studies, but in general, we found lower pollutant concentrations in the present study.

Ventilation in day care centers and sick leave among nursery children

Several studies have reported poor indoor air quality (IAQ) in day care centers (DCCs), and other studies have shown that children attending them have an increased risk of respiratory and gastrointestinal infections. The aim of this study was to investigate whether there is an association between ventilation in DCCs and sick leave among nursery children. Data on child sick leave within an 11-week period were obtained for 635 children attending 20 DCCs. Ventilation measurements included three proxies of ventilation: air exchange rate (ACR) measured with the decay method, ACR measured by the perfluorocarbon tracer gas (PFT) method, and CO2 concentration measured over a 1-week period. All but two DCCs had balanced mechanical ventilation system, which could explain the low CO2 levels measured. The mean concentration of CO2 was 643ppm, exceeding 1000ppm in only one DCC. A statistically significant inverse relationship between the number of sick days and ACR measured with the decay method was found for crude and adjusted analysis, with a 12% decrease in number of sick days per hour increase in ACR measured with the decay method. This study suggests a relationship between sick leave among nursery children and ventilation in DCCs, as measured with the decay method.

Evaluation of air quality in Chengdu, Sichuan Basin, China: are China's air quality standards sufficient yet?

Air quality evaluation is important in order to inform the public about the risk level of air pollution to human health. To better assess air quality, China released its new national ambient air quality standards (NAAQS-2012) and the new method to classify air quality level (AQL) in 2012. In this study, we examined the performance of China's NAAQS-2012 and AQL classification method through applying them, the World Health Organization (WHO) guidelines, and the US AQL classification method to evaluate air quality in Chengdu, the largest city in southwestern China. The results show that annual mean concentrations of PM₁₀, PM₂.₅, SO₂, NO₂, and O₃ at the seven urban sites were in the ranges of 138-161, 87-98, 18-32, 54-70, and 42-57 μg/m(3), respectively, and the annual mean concentrations of CO were in the range of 1.09-1.28 mg/m(3). Chengdu is located in one of the four largest regions affected by haze in China, and PM₁₀ and PM₂.₅ were the top air pollutants, with annual concentrations over 2 times of their standards in NAAQS-2012 and over 7 times of the WHO guidelines. Annual mean concentrations of the pollutants were much lower at the background site (LYS) than at the urban sites, but the annual mean concentrations of PM₁₀ and PM₂.₅ at LYS were 3.5 and 5.7 times of the WHO guidelines, respectively. These suggest that severe air pollution in Chengdu was largely associated with local emissions but also related to regional air pollution. The compliance rates of PM₁₀ , PM₂.₅, SO₂, and O₃ met China's NAAQS-2012 standards four times more frequently than they met the WHO guidelines, as NAAQS-2012 uses the loosest interim target (IT) standards of WHO for these four pollutants. Air pollution in Chengdu was estimated and stated to be less severe using China's classification than using the US classification, as China uses weaker concentration breakpoints and benign descriptions of AQL. Furthermore, China's AQL classification method does not capture the cumulative effects of multiple pollutants, and the risk assessment is mainly based on the exposure-response relationship between air pollutant and human health quantified in the North America and West Europe; these can bring some uncertainties into evaluating the risk to human health in China. In summary, although China greatly improved its NAAQS and AQL classification method in 2012, further improvements are still needed.

Estimation of foreign versus domestic contributions to Taiwan's air pollution

Based on the analysis of observational data obtained over a period of 17 years, this study developed a novel approach estimating long-term changes in the relative contributions of domestic and foreign sources to air pollution levels over the island of Taiwan. The contribution from foreign sources was calculated using data measured at selected coastal monitoring stations under specific meteorological conditions. The domestic contribution was derived by subtracting the foreign contribution from the overall concentration, which was calculated with island-wide monitoring station data averaged using Thiessen polygon area weighting. The trends of mean CO, NO, NO2 and SO2 concentrations in Taiwan were −2.1%, −3.3%, −1.4% and 0% yr−1; while the background concentrations varied by −1.0%, 5.7%, 3.8% and 6.6% yr−1, respectively. These figures suggest that the efforts of Taiwan in reducing air pollution are largely being negated by foreign contributions. Ozone showed a steady increase of 3.3% yr−1, and a portion of this was associated with a 1.0% yr−1 increase in background values. Local and background PM10 concentrations did not show significant long-term trends, but rather strong inter-annual variations associated with dust storm activity in East Asia. The domestic fractions of NO and NO2 respectively decreased from 90% and 85% in 1994 to less than 60% and 70% in 2010. In contrast, the domestic fraction of SO2 decreased from 82% in 1994 to 27% in 2010. The domestic fraction of CO exhibited no obvious trend due to concurrent decreases in local and background contributions. Background O3 values tended to drop across Taiwan due to the titration effect from domestic NO emissions, and the fraction of domestic O3 titration decreased from 50% in the mid-90s to 25% in 2010.

English

Physicochemical and potentially toxic metals statuses of surface water samples collected around the Yauri abattoir were examined. Health risk assessment of the toxicant via ingestion was interpreted by calculating the hazard quotient (HQ). The mean concentration values for total dissolved solid (TDS), total suspended solid (TSS), dissolved oxygen (DO), phosphate, and biochemical oxygen demand (BOD) were 1026.78, 565.22, 5.0, 8.89 and 484.64 mg/L respectively. The values are above those obtained for the control water sample as well as those of international safe limits for water. The values of pH (6.6), sulphate (86.91 mg/L), nitrate (41.45 mg/L) and chemical oxygen demand (COD) (903.30 mg/L) fell within world health organization maximum permissible limits for drinking water. The mean concentrations of Co (6.93 mg/L), Cu (14.45 mg/L), Fe (64.16 mg/L), and Zn (37.14 mg/L) were above both the control and WHO, EU and EPA safe limits for metals in water. On the other hand Cd (11.47 mg/L), Ni (35.49 mg/L), and Pb (41.94 mg/L) had a mean concentration values which are higher than the international standard limits and control water sample. The calculated values of HQ show that Cd, Co, Cu and Ni were of high risk, Fe with a medium and Pb and Zn are of low risk. Correlation coefficients revealed general positive and significant correlations between the pairs of metals in water. The results of this study showed some levels of pollution of the stream water indicating that the activities at the abattoir were contributing to the pollution load of water in the area. Key words: Yauri, abattoir, toxic metals, physicochemical.

Scaling Parameters for Dynamic Diffusion-Reaction over Porous Catalysts

The effect of diffusion resistance in porous solid catalysts on reaction rate during periodic cycling of CO concentration is shown for CO oxidation over Pt/Al2O3 by numerical simulation. At some cycling frequencies, the average reaction rate during cycling is higher than the steady-state rate at the mean CO concentration, as expected for this nonlinear, reactant-inhibited reaction. In order to identify major aspects of dynamic diffusion-reaction behavior, a simple kinetic mechanism that shows the main features of CO oxidation and other reactions with significant inhibition by reactants is investigated. A single dimensionless parameter group, the dynamic diffusion coefficient, is added when going from steady-state to unsteady-state diffusion-reaction equations. In the dynamic diffusion coefficient, the rate at which the gas-phase reactant diffuses is reduced by the surface adsorption capacity of the catalyst. The frequency at which the peak average rate occurs is controlled by the dynamic diffusion coefficient.

Spatio-Temporal Variations in Carbon Monoxide and Carbon Dioxide Levels in Three Motor Parks in Ibadan, Nigeria

Carbon monoxide (CO) and carbon dioxide (CO2) emissions arising from vehicles and combustion processes in motor parks predisposes to adverse health outcomes and associated health risks. There is dearth of studies and data on air quality in motor parks in Nigeria, hence, the need to assess the levels of CO and CO2 and their relationship with meteorological parameters in three major motor parks in Ibadan, Nigeria. A cross-sectional comparative design was adopted for this study. Akinyele Motor Park (AMP) in Akinyele Local Government Area (LGA), Iwo Road Motor Park (IMP) in Ibadan North East LGA and New Garage Motor Park (NMP) in Ibadan South West LGA were purposively selected and levels of CO and CO2 were monitored for 2 months with appropriate gas meters, meteorological parameters were also monitored using Ventus W155 wireless weather station. Values obtained were compared with WHO and ASHRAE guideline limits. Descriptive and inferential statistics were used for data analysis at p=0.05. CO concentrations (ppm) for AMP, IMP and NMP ranged from 2.0-106.0, 2.0 – 83.0 and 2.0 – 90.0 respectively while the mean CO2 concentrations (ppm) were 395.4 ± 30.5, 356.3 ± 57.1 and 388.1 ± 42.1 respectively. There was a significant positive correlation between CO and CO2 (r=0.258, p=0.000) and also with four meteorological parameters; temperature (r=0.164), rainfall (r= 0.105), heat index (r= 0.134) and dew point (r= 0.127) (p<0.05). A positive correlation was also found between CO2 and four meteorological parameters; temperature (r= 0.276, p=0.000), rainfall (r=0.125), heat index (r= 0.232, p=0.003) and dew point (r=0.028). For the three motor parks, CO concentrations (ppm) were 80% higher than WHO guideline of 9 ppm for 8 hour monitoring. Mean CO2 concentrations (ppm) were within ASHRAE guideline limit of 400 ppm. The study showed that meteorology has influence on CO and CO2 concentrations and motor park users are exposed to high levels of CO. Routine monitoring of CO and CO2 is recommended in order to ensure these emissions do not exceed guideline limits.

Associations between Natural Ventilation for the Child's Bedroom during Night and Childhood Asthma in Shanghai, China

From March 2013 to December 2014, we conducted a case-control study and inspected 454 residences with asthmatic or non-asthmatic children from six districts in Shanghai. Carbon dioxide (CO2) were passively measured 24hours in the child's bedroom. We took the average concentration of CO2 during 00:00 to 06:00 as an indicator for the status of natural ventilation in the child's bedroom during night and investigated its association with childhood asthma. A total of 45.6% (n = 203) residences had CO2 average concentrations higher than 1000ppm. The mean CO2 concentration ± standard deviation was 1123 ± 741ppm (range: 367 to 4595ppm). CO2 average concentrations in the residences measured in autumn and in summer were significantly lower than measured in winter. No significant differences were found among CO2 average concentrations among Case group and Control group in total and in different measured seasons. More deeply analyses were warranted.

Sensitivity of simulated CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; concentration to regridding of global fossil fuel CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; emissions

Abstract. Errors in the specification or utilization of fossil fuel CO2 emissions within carbon budget or atmospheric CO2 inverse studies can alias the estimation of biospheric and oceanic carbon exchange. A key component in the simulation of CO2 concentrations arising from fossil fuel emissions is the spatial distribution of the emission near coastlines. Regridding of fossil fuel CO2 emissions (FFCO2) from fine to coarse grids to enable atmospheric transport simulations can give rise to mismatches between the emissions and simulated atmospheric dynamics which differ over land or water. For example, emissions originally emanating from the land are emitted from a grid cell for which the vertical mixing reflects the roughness and/or surface energy exchange of an ocean surface. We test this potential "dynamical inconsistency" by examining simulated global atmospheric CO2 concentration driven by two different approaches to regridding fossil fuel CO2 emissions. The two approaches are as follows: (1) a commonly used method that allocates emissions to grid cells with no attempt to ensure dynamical consistency with atmospheric transport and (2) an improved method that reallocates emissions to grid cells to ensure dynamically consistent results. Results show large spatial and temporal differences in the simulated CO2 concentration when comparing these two approaches. The emissions difference ranges from −30.3 TgC grid cell−1 yr−1 (−3.39 kgC m−2 yr−1) to +30.0 TgC grid cell−1 yr−1 (+2.6 kgC m−2 yr−1) along coastal margins. Maximum simulated annual mean CO2 concentration differences at the surface exceed ±6 ppm at various locations and times. Examination of the current CO2 monitoring locations during the local afternoon, consistent with inversion modeling system sampling and measurement protocols, finds maximum hourly differences at 38 stations exceed ±0.10 ppm with individual station differences exceeding −32 ppm. The differences implied by not accounting for this dynamical consistency problem are largest at monitoring sites proximal to large coastal urban areas and point sources. These results suggest that studies comparing simulated to observed atmospheric CO2 concentration, such as atmospheric CO2 inversions, must take measures to correct for this potential problem and ensure flux and dynamical consistency.